scholarly journals PHASE COMPOSITION, SUBSTRUCTURE AND RESIDUAL MACROSTRESSES IN THE SURFACE LAYER OF A TAPE OBTAINED BY ELECTRIC CONTACT WELDING

2021 ◽  
pp. 802-808
Author(s):  
Андрей Иванович Фомин ◽  
Николай Александрович Панькин
Keyword(s):  
Surface Layer ◽  
Phase Composition ◽  
Residual Stresses ◽  
Intermediate Layer ◽  
Nickel Powder ◽  
Electrical Contact ◽  
Large Temperature ◽  
Electric Contact ◽  
Processing Technologies ◽  
Contact Welding

Методами рентгенографии и электронной микроскопии исследован поверхностный слой чугуна ВЧ50-2 после его обработки электроконтактной приваркой. В качестве присадочного материала использовалась лента из стали 50ХФА. Применялись технологии обработки с созданием промежуточного слоя из никелевого порошка ПГН-12Н-01 и без него. Получены результаты о фазовом составе, субструктуре и остаточных напряжениях. Исследуемая система состоит из фаз a - Fe и у - Fe . Параметры субструктуры (микродеформации и измельчение блоков) имеют одинаковые значения для различных режимов электроконтактной приварки. Остаточные напряжения носят растягивающий характер и уменьшаются при создании промежуточного слоя из никелевого порошкового материала. Основной механизм их образования - термические воздействия на материал, обрабатываемый электроконтактной приваркой. Установлено, что после электроконтактной приварки ленты могут образовываться трещины, их ориентация преимущественно параллельно обрабатываемой поверхности обусловлена наличием большого градиента температур. The surface layer of DI50-2 cast iron after its processing by electric contact welding has been investigated by methods of X-ray diffraction and electron microscopy. A 50HVA steel strip was used as a filler material. Processing technologies were used with the creation of an intermediate layer of nickel powder PC-12N-01 and without it. Results on phase composition, substructure and residual stresses are obtained. The system under study consists of a-Fe and у-Fe phases. Substructure parameters (microstrain and block refinement) have the same values for different modes of electrical contact welding. Residual stresses are of a tensile nature and decrease when an intermediate layer of nickel powder material is created. The main mechanism of their formation is thermal effects on the material processed by electrocontact welding. Cracks may form after electrical contact welding of the tape. They are oriented mainly parallel to the surface to be treated and are due to the presence of a large temperature gradient.

Investigation of pre-sprayed powders for electric contact welding

2020 ◽  
pp. 143-149
Author(s):  
Dinar R. Masalimov ◽  
Roman R. Galiullin ◽  
Rinat N. Sayfullin ◽  
Azamat F. Fayurshin ◽  
Linar F. Islamov
Keyword(s):  
Adhesion Strength ◽  
Electrical Contact ◽  
Research Purpose ◽  
Flame Spraying ◽  
Powder Materials ◽  
Electric Contact ◽  
Metal Powders ◽  
Unstable Flow ◽  
Gas Flame ◽  
Contact Welding

There are a number of difficulties in the electrical contact welding of powder materials: shedding of powder from the surface of a cylindrical part, impossibility of hardening the layer during welding due to flushing of the powders with coolant and unstable flow of powder into the welding zone. One solution is pre-spraying the powder in some way. (Research purpose). The research purpose is investigating the possibility of electric contact welding of metal powders preliminarily sprayed by a gas-flame method, namely, adhesion strength and losses during preliminary gas-flame spraying of powders. (Materials and methods) Powders of grades PG-NA-01, PrKhIIG4SR, PRZh3.200.28 were sprayed onto flat samples of St3 steel, polished to a roughness of Ra 1.25. The strength of powder adhesion to the base was studied by the cut method. (Results and discussion) The percentage loss of the powder as a whole is 3-23 percent for all the distances studied. The greatest powder losses appear at a distance of more than 180 millimeter from the tip of the burner for powders of grades PG-NA-01 and PrKhIIG4SR. The smallest powder losses were observed for PrZh3.200.28 powder, which totaled 3-7 percent. The maximum adhesion strength of the sprayed powders to the surface was 22.1 megapascals' when spraying the PG-NA-01 powder. The adhesion strength of powders of the grades PrKhIIG4SR and PrZh3.200.28 is small and amounts to 0.2-3 megapascals'. (Conclusions) The use of preliminary flame spraying of powders for their further electric contact welding is possible using PG-NA-01 grade powder, while the best adhesion to the base (that is more than 20 megapascals') is achieved with a spraying distance of 120-140 millimeter. The smallest powder losses during flame spraying are achieved at a spraying distance of 100-160 centimeters', at which the powder loss for the studied grades was 4-12 percent.

Effect of diamond burnishing parameters on the state of the processed surface layer of billets made of high-strength "30ХГСН2А-ВД" steel

2020 ◽  
pp. 82-86
Author(s):  
A.N. Shvetsov ◽  
D.L. Skuratov
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Strain Hardening ◽  
Processing Speed ◽  
Synthetic Diamond ◽  
High Strength ◽  
The State ◽  
Diamond Burnishing

The influence of the burnishing force, tool radius, processing speed and feed on the distribution of circumferential and axial residual strses, microhardness and the depth of strain hardening in the surface layer when pr ssing of "30ХГСН2А-ВД" steel with synthetic diamond "ACB-1" is considered. Empirical dependencies determining these parameters are given. Keywords diamond burnishing, strain hardening depth, circumferential residual stresses, axial residual stresses, microhardness. [email protected], [email protected]

Parameters of the Plastic Deformation of a Filler Wire during Electrical-Contact Welding

2020 ◽  
Vol 2020 (13) ◽  
pp. 1491-1495
Author(s):  
M. Z. Nafikov ◽  
I. I. Zagirov ◽  
Kh. T. Karimov ◽  
R. F. Masyagutov
Keyword(s):  
Plastic Deformation ◽  
Electrical Contact ◽  
Filler Wire ◽  
Contact Welding

scholarly journals Thermal Effects on Surface and Subsurface Modifications in Laser-Combined Deep Rolling

2021 ◽  
Vol 5 (2) ◽  
pp. 55
Author(s):  
Robert Zmich ◽  
Daniel Meyer
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Thermal Loads ◽  
Deep Rolling ◽  
Mechanical Loads ◽  
Thermomechanical Process ◽  
Compressive Stresses ◽  
New Process ◽  
Negative Effect ◽  
Compressive Residual Stresses

Knowledge of the relationships between thermomechanical process loads and the resulting modifications in the surface layer enables targeted adjustments of the required surface integrity independent of the manufacturing process. In various processes with thermomechanical impact, thermal and mechanical loads act simultaneously and affect each other. Thus, the effects on the modifications are interdependent. To gain a better understanding of the interactions of the two loads, it is necessary to vary thermal and mechanical loads independently. A new process of laser-combined deep rolling can fulfil exactly this requirement. The presented findings demonstrate that thermal loads can support the generation of residual compressive stresses to a certain extent. If the thermal loads are increased further, this has a negative effect on the surface layer and the residual stresses are shifted in the direction of tension. The results show the optimum range of thermal loads to further increase the compressive residual stresses in the surface layer and allow to gain a better understanding of the interactions between thermal and mechanical loads.

Reduction of Residual Stresses in Medium Density Fibreboard. Part 1. Taguchi Analysis

Holzforschung ◽  
2001 ◽  
Vol 55 (1) ◽  
pp. 67-72 ◽  
Author(s):  
J. van Houts ◽  
D. Bhattacharyya ◽  
K. Jayaraman
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Internal Bond ◽  
Tensile Modulus ◽  
Thickness Swell ◽  
Subsequent Paper ◽  
Medium Density ◽  
Medium Density Fibreboard ◽  
Taguchi Analysis ◽  
Dissection Method

Summary This paper demonstrates how the Taguchi method of experimental design can be utilised to investigate methods for relieving the residual stresses present in medium density fibreboard (MDF). Panels have been subjected to heat, moisture and pressure, and after equilibration to room conditions, the changes in residual stresses through various layers have been measured using the dissection method. The application of heat and/or moisture has reduced the magnitude of residual stresses while generally the application of pressure has no effect on these stresses. The subsequent paper in this series uses Taguchi analysis to investigate how other board properties such as thickness swell, internal bond strength, surface layer tensile modulus and surface layer tensile strength are affected by the different treatment methods.

Surface Modification Analysis after Shot Peening of AA 7075 in Different States

2013 ◽  
Vol 768-769 ◽  
pp. 519-525 ◽  
Author(s):  
Sebastjan Žagar ◽  
Janez Grum
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Residual Stresses ◽  
Aluminium Alloy ◽  
Shot Peening ◽  
Fatigue Testing ◽  
Stress Profile ◽  
Treatment Conditions ◽  
Stress Profiles ◽  
Compressive Residual Stresses

The paper deals with the effect of different shot peening (SP) treatment conditions on the ENAW 7075-T651 aluminium alloy. Suitable residual stress profile increases the applicability and life cycle of mechanical parts, treated by shot peening. The objective of the research was to establish the optimal parameters of the shot peening treatment of the aluminium alloy in different precipitation hardened states with regard to residual stress profiles in dynamic loading. Main deformations and main residual stresses were calculated on the basis of electrical resistance. The resulting residual stress profiles reveal that stresses throughout the thin surface layer of all shot peened specimens are of compressive nature. The differences can be observed in the depth of shot peening and the profile of compressive residual stresses. Under all treatment conditions, the obtained maximum value of compressive residual stress ranges between -200 MPa and -300 MPa at a depth between 250 μm and 300 μm. Comparison of different temperature-hardened aluminium alloys shows that changes in the Almen intensity values have greater effect than coverage in the depth and profile of compressive residual stresses. Positive stress ratio of R=0.1 was selected. Wöhler curves were determined in the areas of maximum bending loads between 30 - 65 % of material's tensile strength, measured at thinner cross-sections of individual specimens. The results of material fatigue testing differ from the level of shot peening on the surface layer.

Research of Electric Contact Welding by a Wire at Restoration of Details of Cars

2021 ◽  
Author(s):  
Dmytro Marchenko ◽  
Aleksandr Dykha ◽  
Kateryna Matvyeyeva ◽  
Viacheslav Kurepin
Keyword(s):  
Electric Contact ◽  
Contact Welding
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